Method for Controlling a Casting Plant

ABSTRACT

A method for controlling a casting plant has at least one mould for receiving a fluid material, the fluid material solidifying in the mould during a solidifying time, at least one process parameter being detected during the production process and the solidifying time being determined in accordance with the process parameter detected.

The invention relates to a method for controlling a casting plant havingat least one mould for receiving a fluid material, the fluid materialsolidifying in the mould during a solidifying time. The inventionfurther relates to a casting plant having at least one mould, a castingplant system comprising this casting plant, a computer programme and acomputer programme product.

Motor components but also other components are nowadays produced by acasting process in casting plants. During the casting process, a solidmember having a specific shape in accordance with the shape of the mouldis produced from a fluid material after the material has solidified. Inthis instance, a constant concern is to configure the production processin an efficient manner and in particular to improve the production speedin addition to reducing incorrectly produced components.

During casting, the efficiency of the production process is particularlydependent on the solidifying time, that is to say, the time during whichthe initially fluid material cools and solidifies in a mould of thecasting plant so that it can be removed from the mould. The solidifyingtime also significantly determines the cycle time and consequently theproduction rate of the production process.

In conventional methods for controlling a casting plant of the priorart, the solidifying time is a constant time period. In other words, acast component is always removed from the mould after the same time. Inthis instance, the solidifying time is generally configured at maximumload with regard to the operation of the casting plant in order toincrease production.

However, a problem in the prior art is that, on the one hand, thecasting process is subjected to a plurality of non-constant factorswhich can be influenced only to a limited extent or not at all. Thisincludes, for example, the ambient temperature of the casting plant orthe temperature of the materials used.

On the other hand, undesirable and unavoidable interruptions to thecasting process occur again and again, for example, as a result ofdefective components, maintenance work, technical errors, etc. After aninterruption, the casting plant has to be re-started once more and themould in particular has to be brought back to temperature. However,since the solidifying time is configured to be constant and foroperation at maximum load, interruptions and unavoidable influences withrespect to the casting process result in defective components. On theother hand, a constant solidifying time may also result in a componentremaining in the mould for longer than is necessary.

Therefore, an object of the present invention is to provide a method forcontrolling at least one casting plant, which method allows moreefficient production of components, particularly even under non-optimumconditions.

The object which is previously derived and set out is achieved accordingto a first aspect of the invention by a method for controlling a castingplant having at least one mould for receiving a fluid material, thefluid material solidifying in the mould during a solidifying time. Themethod comprises the steps that at least one process parameter isdetected during the production process and the solidifying time isdetermined in accordance with the process parameter detected.

Unlike the prior art, the solidifying time is not predetermined as aconstant time according to the invention but instead it is variable andis determined during the production process in accordance with at leastone process parameter. In other words, the solidifying time may changeduring the production process in accordance with a detected processparameter.

A casting plant having at least one mould is controlled with the methodaccording to the invention. A mould which may in principle have anyshape in accordance with the set shape of the component to be producedis filled with a fluid material. The initial material may preferably bea fluid metal. In order to fluidise a metal, it is heated accordingly.

The fluid and hot material introduced into the mould cools in the mouldand solidifies to form a solid member. The solidifying time, that is tosay, the time period between the mould being filled and the time ofremoval of the cast component, is determined according to the inventionin accordance with a process parameter detected during the productionprocess.

The term process parameter is intended to be understood to be aparameter which is characteristic of the casting process or whichinfluences it directly or indirectly. In particular, the processparameter is a parameter which is characteristic of the solidifying timeor which influences it directly or indirectly.

By the solidifying time being determined (automatically) according tothe invention in accordance with a parameter detected during theproduction process, the reject rate can be reduced. The production rateand the efficiency of the production method can also be significantlyincreased even under non-optimum operating conditions. In particular,interruptions to the production process and unavoidable influences maybe taken into consideration by the method according to the invention.Even small reductions in the cycle time in the order of seconds resultin significantly higher production rates.

In principle, the at least one process parameter can be detected at anytimes. According to a first embodiment of the method according to theinvention, a current process parameter can be detected during a castingprocess of a component to be produced. The term casting process isintended to be understood to be an individual casting operation of acomponent during the production process of a large number of components.In particular, at least one current process parameter can be detectedfor each component to be cast during the casting process of thecorresponding component. The solidifying time for the component(currently) to be produced can preferably be determined in accordancewith the detected current process parameter. In other words, thesolidifying time of the component to be cast may depend (directly) on acurrent process parameter. Current influences and particularly changeswith respect to the casting process can be taken into consideration (ina timely manner). In particular (automatic) real-time control of thesolidifying time is possible. The cycle time and quality can beimproved.

According to a preferred embodiment of the method according to theinvention, the at least one process parameter can be detectedcontinuously. Continuous detection of a process parameter at leastduring the casting process of a component (currently) to be cast resultsin exact and (constantly) current measurement values. Alternatively, theprocess parameter may be detected at predeterminable time intervals, inparticular at periodic time intervals. The time intervals mayparticularly be selected so that the measurement values are sufficientlycurrent to be able to take into consideration, for example, influenceswhich act on the casting process in an adequate and timely manner. Forexample, a value may be detected every second, preferably every halfsecond.

It will be understood that a plurality of different process parametersof the production process, in particular the casting process, can bedetected. Different process parameters can also be detected in differentmanners, that is to say, continuously or at predeterminable timeintervals.

Furthermore, the determination of the solidifying time can be carriedout according to another embodiment of the method according to theinvention in accordance with a comparison of the detected processparameter with at least one set process parameter. A set processparameter, such as a limit value, may be predetermined. By comparing the(current) process parameter with a suitable set process parameter, thesolidifying time can readily be determined. For example, the set processparameter can be predetermined so that, when the current processparameter exceeds or falls below the set process parameter, thisindicates the time from which the mould can be opened. In other words,at least one condition can be predetermined so that, when the conditionis fulfilled, adequate solidifying of the material has been carried outand the cast component can be removed.

At least two set process parameters may preferably be provided for aprocess parameter. An upper and a lower limit value which define apermitted range may further be predetermined. Only if the currentprocess parameter is in this range can the mould be opened. Furthermore,additional set criteria can be predetermined. For example, it may beconsidered in a continuously changing process parameter whether it is(currently) changing in an increasing or decreasing manner.

In principle, different process parameters of the production process aresuitable for determining the solidifying time.

Process parameters which characterise or influence the solidifying timemay preferably be detected. It has been recognised that the temperatureof the mould or the temperature of the material located in the mould isparticularly suitable for determining the solidifying time. Inparticular, it is possible to derive from the temperature of thematerial in the mould whether the initially fluid material hassolidified (sufficiently) and whether the mould can be opened. A setvalue temperature may preferably be predetermined, at which it isensured that the fluid material used has solidified to such an extentthat a cast component can be removed. In other words, the optimumremoval time can be determined for each component. The removal time,that is to say, the variable solidifying time, may particularly dependon the current temperature of the material or component. On the onehand, an excessively early removal time at which adequate solidifyinghas not yet begun can be prevented. On the other hand, unnecessarilylong solidifying times can be prevented. The cycle time can be improvedwith a simultaneous reduction in the number of defective components.

As already described, additional criteria may be predetermined. Forexample, it may be considered whether the temperature of the mould orthe temperature of the material in the mould is increasing ordecreasing. For instance, when the mould is filled, the detectedtemperature may initially increase and accordingly initially be below aset value. In order to nevertheless ensure that the material hassolidified, the temperature progression can be taken into consideration.It is possible to conclude from a decreasing temperature progressionthat the material is cooling and solidifying. In addition to reaching,falling below or exceeding a set temperature, there may be provision forthe temperature progression to be decreasing in addition to determiningthe solidifying time.

It will be understood that the temperatures of the mould and thematerial in the mould can be detected according to other variants of theinvention.

Furthermore, according to another embodiment of the method, thesolidifying time of the component to be produced can be determined inaccordance with the solidifying time of at least one previously producedcomponent. In Particular, results from previous casting processes may bestored and considered. For example, it is possible to conclude adefective measurement from an unusual discrepancy between the currentsolidifying time and the solidifying time of the previously castcomponent.

In order to prevent excessively early opening of the mould in the eventof incorrect detection of the (current) process parameter, at least oneset solidifying time may preferably be predetermined. For example, atleast one minimum set solidifying time may be predetermined. The minimumset solidifying time may particularly be selected so that at leastadequate solidifying of the material has begun, which solidifyingprevents fluid material from flowing out of the mould when the mould isopened and resulting in damage to the casting plant or other devices.Furthermore, a maximum set solidifying time may be predetermined.Incorrect measurement of the at least one process parameter may resultnot only in a condition, such as a set process parameter being reached,being achieved too early, but also in a condition not being achieved orbeing achieved too late. In order also to allow removal in thisinstance, a maximum set solidifying time may be predetermined, the mouldbeing able to be opened and the component being able to be removed(always) when the maximum set solidifying time has been reached. It willbe understood that corresponding errors can be displayed for a user.

According to a particularly preferred embodiment of the method accordingto the invention, the above-described criteria, in accordance with whichthe solidifying time, that is to say, the removal time of the castcomponent, can be determined, may be taken into consideration in aformula. For example, different conditions can be associated with eachother logically in a formula. In particular, a set value temperaturebeing reached may be associated with the conditions that the temperatureprogression is decreasing and a minimum solidifying time has beenexceeded.

According to another embodiment of the method, the at least one setprocess parameter may further be determined before the productionprocess. All the set values, in particular a previously describedformula, may preferably be determined before the production process. Inparticular, the at least one set solidifying time can be establishedbefore the production process.

According to another preferred embodiment, the at least one set processparameter can be determined in accordance with the fluid material, thecasting plant, the state of the casting plant and/or the shape of themould. For example, different fluid materials may have differentsolidifying temperatures. Therefore, the at least one set temperaturemay be different for different materials. Similarly, the mould shapeused, for example, the size, diameter thereof, etcetera, may requiredifferent set process parameters in order to achieve optimum results.However, different casting plant types and the state of the castingplant may also have some influence on an optimum solidifying time. Itwill be understood that other criteria may be used for determining theset process parameter. It will also be understood that a set solidifyingtime can also be determined in a similar manner in addition to a setprocess parameter.

There may further be provision for the at least one set value parameteralso to be able to be determined (again) during the production processat predeterminable time intervals.

Another aspect of the invention is a casting plant having at least onemould for receiving a fluid material. In the casting plant, there isprovided at least one sensor device which is configured to detect atleast one process parameter during the production process and there isprovided at least one control device which is configured to determinethe solidifying time in accordance with the detected process parameter.

The casting plant is particularly constructed to carry out theabove-described method.

The casting plant further comprises at least one mould having apredeterminable shape. The shape is particularly dependent on thecomponent to be produced. The mould may be filled with a fluid material,such as a metal or the like. After the material has solidified, themould may be opened and the solidified component may be removed.

At least one suitable sensor device is further provided in order todetect at least one previously mentioned process parameter during theproduction process and in particular during a casting process.

A control device is further provided. The control device, for example, amicrocomputer, a Digital Signal Processor (DSP) or the like, isconfigured to process the detected process parameter and to determinethe optimum solidifying time, that is to say, the removal time, for thecast component in accordance with the process parameter.

The production rate and the efficiency of the production method can besignificantly increased even under non-optimum operating conditions.

According to a first embodiment of the casting plant according to theinvention, the sensor device may be a temperature sensor. Thetemperature sensor may particularly be arranged on or in the mould. Aprocess parameter which is significant for the casting process can bedetected by means of a suitable temperature sensor.

According to a preferred embodiment of the casting plant according tothe invention, the temperature sensor may be arranged in such a mannerthat the temperature of the material in the mould can be detected. Asalready described, the solidifying time actually required is dependent(inter alia) on the temperature of the material in the mould. Forexample, the temperature of the mould can be measured. The temperatureof the material in the mould can be derived from this temperature.

In principle, the temperature of the material in the mould may bedetected in a contactless manner or with contact. In a particularlypreferable manner, the at least one temperature sensor may be arrangedin such a manner that the temperature sensor directly contacts thematerial in the mould. The temperature can be detected in a particularlyprecise manner. The at least one set temperature value can thereby beset practically without any tolerance as a result of measurementinaccuracies. The cycle time may be significantly reduced without anyloss of quality.

Another aspect of the invention is a casting system comprising at leastone above-described casting plant and a central control unit configuredto determine at least one set process parameter.

The casting system may also have two or more casting plants which cancommunicate with the central control unit. The central control unit, inparticular a central processing device having a database, may be in theform of a superordinate control unit. For example, informationconcerning the casting plant, such as the state of the casting plant,the shape of the mould, etcetera, and concerning the components to beproduced and initial materials, can be stored in the database. At leastone optimum set process parameter, preferably a previously describedformula for determining the solidifying time, can be derived from thatinformation. Information from a plurality of casting plants which areconnected to the central control unit can further advantageously be usedin order to determine an optimum set process parameter, preferably aformula for determining the solidifying time.

Another aspect of the invention is a computer programme havinginstructions which can be carried out on a processor in such a mannerthat a casting plant is controlled by means of the above-describedmethod.

Yet another aspect of the invention is a computer programme productcomprising an above-described computer programme having instructionswhich can be carried out on a processor in such a manner that a castingplant is controlled by means of the above-described method.

According to another embodiment, there is provided a method forcontrolling a casting plant having at least one mould for receiving afluid material, the fluid material solidifying in the mould during asolidifying time, at least one process parameter being detected duringthe production process and the solidifying time being determined inaccordance with the detected process parameter.

According to another embodiment, a current process parameter is detectedduring a casting process of a component to be produced and thesolidifying time for the component to be produced is determined inaccordance with the detected, current process parameter.

According to another embodiment, the process parameter is detectedcontinuously or at predeterminable time intervals.

According to another embodiment, the determination of the solidifyingtime is carried out in accordance with a comparison of the detectedprocess parameter with at least one set process parameter.

According to another embodiment, the process parameter is thetemperature of the mould or the process parameter is the temperature ofthe material in the mould.

According to another embodiment, the solidifying time of the componentto be produced is determined in accordance with the solidifying time ofat least one previously produced component.

According to another embodiment, at least one set solidifying time ispredetermined.

According to another embodiment, at least the set process parameter isdetermined before the production process.

According to another embodiment, the set process parameter is determinedin accordance with the material, the casting plant, the state of thecasting plant and/or the mould shape.

According to another embodiment, a casting plant having at least onemould for receiving a fluid material is provided, there being providedat least one sensor device configured to detect at least one processparameter during the production process and there being provided atleast one control device configured to determine the solidifying time inaccordance with the detected process parameter.

According to another embodiment, the sensor device is a temperaturesensor, the temperature sensor particularly being arranged on or in themould.

According to another embodiment, the temperature sensor is arranged insuch a manner that the temperature of the material in the mould can bedetected.

There are now a large number of possibilities of configuring anddeveloping the method according to the invention for controlling atleast one casting plant, the casting plant according to the invention,the casting plant system according to the invention, the computerprogramme according to the invention and the computer programme productaccording to the invention. To this end, reference may be made, on theone hand, to the patent claims which arc subordinate with respect to theindependent patent claims and, on the other hand, to the description ofembodiments in conjunction with the drawings, in which:

FIG. 1 is a schematic view of a first embodiment of a casting plantsystem having a casting plant according to the present invention; and

FIG. 2 is a flow chart of an embodiment of a method for controlling acasting plant according to the present invention.

FIG. 1 is a schematic view of a first embodiment of a casting plantsystem 2 having an exemplary casting plant 4 according to the presentinvention.

The casting plant 4 illustrated is configured to produce, in particularto cast, components 6. For example, motor components or the like can becast. To this end, a fluid material 8, such as a fluid metal, isprovided. The metal may be in particular aluminium or an aluminiumalloy.

The fluid material 8 is introduced into a mould 10, also referred to asa casting mould 8. In order to produce components 6 having cavities, itis further possible to provide mould substances 12. Cores can, forexample, be formed with the mould substances 12 in order to producesubsequent cavities in the components 6. For example, suitable sands areused as mould substances 12 for a core.

The casting plant 4 further has a control device 14. The control device14 may be configured to control the casting plant 4 or the castingprocess. The control device 14 may have suitable processing means 16,such as a processor, storage means, interfaces, etcetera, in order topredetermine different control parameters for the casting process. Forexample, it is possible to predetermine cooling parameters, heatingparameters for heating mould portions of the tool mould and/or suitablecutting and supply parameters.

The control device 14 is particularly configured to determine thesolidifying time, that is to say, the removal time, as will be set outin greater detail below.

In the present embodiment, the casting plant 4 further comprises asensor device 18. The sensor device 18 is in particular a temperaturesensor 18 for detecting the temperature of the mould 10 and/or thematerial in the mould 10.

The temperature of the material in the mould 10 can preferably bedetected directly. For example, a temperature sensor 18 can be arrangedin such a manner that it directly contacts the material in the mould 10.Alternatively or additionally, the temperature of the mould 10 can bemeasured. For example, the temperature of the material in the mould 10can be derived from that temperature.

The temperature sensor 18 detects at predeterminable time intervals orcontinuously at least one of the above-mentioned temperatures. Thetemperature values detected can be provided for the control device 14 ina suitable form for further processing.

It will be understood that, according to other variants of the presentinvention, a plurality of temperature sensors 18 may be provided inorder to detect the temperature of the mould 10 and/or the material inthe mould at different locations. It will further be understood thatadditional detection devices may be provided, for example, in order todetect the ambient temperature and the like.

The casting plant 4 may further be in communication connection with acentral control unit 20. In principle, a wireless or wired communicationconnection may be provided.

The central control unit 20 may comprise processing means (notillustrated) and a database. The central control unit 20 may further beconnected to additional casting plants (not illustrated).

The operation of the casting plant 4 according to FIG. 1 is described ingreater detail below with reference to FIG. 2. FIG. 2 is a flow chart ofan embodiment of a method for controlling a casting plant 4 according tothe present invention.

In a first step 201, initially before the beginning of the productionprocess, that is to say, before the casting process of a first component4, at least a first set process parameter can be determined. Thedetermination of the set process parameter may be dependent inparticular on the material 8, the casting plant 4, the state of thecasting plant 4, the mould shape, the component 6 to be produced,etcetera.

It will be understood that a plurality of set process parameters may bedetermined. In particular at least one limit value for at least oneprocess parameter may be determined. Furthermore, at least one setsolidifying time may be predetermined. At least one minimum setsolidifying time and one maximum set solidifying time may preferably bedetermined.

Furthermore, not only set parameters but also a formula for determiningthe optimum solidifying time may preferably be determined, in particularin accordance with the above-mentioned criteria, the formula preferablybeing able to be dependent on a set solidifying time, set processparameter and detected process parameters. For example, individualconditions can be associated with each other logically.

According to the embodiment explained in greater detail below, there maybe predetermined a minimum set temperature, a minimum set solidifyingtime, a maximum set solidifying time and the condition that thetemperature progression is decreasing, the individual connections beingable to be associated with each other logically.

The set temperature value may be, for example, in the range between 350°C. and 600° C. in the case of aluminium as the material. The minimum setsolidifying time may be in the range between 80 seconds and 180 seconds.The maximum set solidifying time may be in the range between 100 secondsand 250 seconds.

The determination of the at least one set process parameter or a formulamay be determined by the control device 14 of the casting plant 4.However, a superordinate control device 20, for example, a centralcontrol unit 20 having a database for determining the at least one setprocess parameter may preferably be provided. The superordinate controldevice 20 may particularly be configured to monitor and control aplurality of casting plants.

In a subsequent step 202, the fluid material can be introduced into themould 10. At the same time, a time measuring device can be started. Forexample, the time measuring device may be started when the fillingoperation is started or when the filling operation finishes.

In a subsequent step 203, the fluid material can cool and solidify. Atleast one process parameter may be detected during the casting process.In the present embodiment, the temperature of the material in the mould10 is continuously detected by a sensor device 18. It will be understoodthat the temperature can be detected continuously during the entireproduction process and not only during the casting operation.

The control device 14 can particularly be configured to compare thecurrently detected temperature of the material with the optimum settemperature.

If the control device 14 establishes that the optimum set temperaturehas been reached or the value has fallen below it, it can initiallyfurther be investigated whether the temperature progression isdecreasing. Furthermore, it can additionally be investigated whether theminimum set solidifying time has already been exceeded. To this end, thevalue of the time measuring device can be compared with the minimum setsolidifying time.

If the conditions are complied with, the control unit 14 can cause themould 10 to be opened and the component 6 to be removed in a step 204.After the component 6 has been removed, the mould 10 can be closedagain, the time measuring device can be reset and the method can becontinued in accordance with step 202.

An alternative removal condition may be reaching the maximum setsolidifying time. The value of the time measuring device may becompared, preferably continuously, with at least the maximum setsolidifying time. Even if the temperature of the material has not yetreached the set temperature, it is nevertheless possible for the castcomponent 6 to be removed. In this instance, there is a measurementerror in all probability.

However, the mould 10 is not opened if, although the current temperatureof the material is below the set temperature, the temperatureprogression is increasing. In the present embodiment, the mould 10 isalso not opened if, although the current temperature of the material isbelow the set temperature, the minimum set solidifying time has not yetbeen reached.

The last instances mentioned indicate a technical error. For example,the detection device 18 may be defective. In this instance, the mould 10may initially be opened in step 204 after the minimum or maximum setsolidifying time has expired. Subsequently, the production process maybe interrupted or ended (step 205). Suitable measures for eliminatingthe technical error may be taken.

1. A method for controlling a casting plant comprising at least onemould for receiving a fluid material, the fluid material solidifying inthe mould during a solidifying time, at least one process parameterbeing detected during the production process, the process parameterbeing the temperature of the material in the mould, the solidifying timebeing determined in accordance with the process parameter detected, andthe determination of the solidifying time being carried out inaccordance with a comparison of the process parameter detected with atleast one set process parameter, wherein at least the at least one setprocess parameter is determined before the production process and atleast one set process parameter is determined again during theproduction process at predeterminable time intervals.
 2. The methodaccording to claim 1, wherein the process parameter is detectedcontinuously or at predeterminable time intervals.
 3. The methodaccording to claim 1, wherein the solidifying time of the component tobe produced is determined in accordance with the solidifying time of atleast one previously produced component.
 4. The method according toclaim 1, wherein at least one set solidifying time is predetermined. 5.The method according to claim 4, wherein the set process parameter isdetermined in accordance with the material, the casting plant, the stateof the casting plant and/or the shape of the mould.
 6. A casting planthaving at least one mould for receiving a fluid material, the castingplant being formed to carry out the method according to claim 1, whereinat least one sensor device is configured to detect at least one processparameter during the production process and at least one control deviceis configured to determine the solidifying time in accordance with thedetected process parameter.
 7. The casting plant according to claim 6,wherein the sensor device is a temperature sensor, the temperaturesensor being arranged on or in the mould.
 8. The casting plant accordingto claim 7, wherein the temperature sensor is arranged in such a mannerthat the temperature of the material in the mould can be detected. 9.The casting system comprising at least one casting plant according toclaim 6 and a central control unit configured to determine the at leastone set process parameter.
 10. A computer program having instructionswhich can be carried out on a processor in such a manner that a castingplant is controlled by the method according to claim
 1. 11. The computerprogram product comprising a computer program having instructions whichcan be carried out on a processor in such a manner that a casting plantis controlled by the method according to claim 1.